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Another buzzing sub-woofer problem

By redmike
Apr 24, 2010
  1. Hi,

    Sub-woofer only has a two pin a/c plug.

    Connecting input cable is single wire with a stereo mini-phone jack on each end.

    If I plug the sub-woofer into the a/c there is no buzzing until I plug a cable (unattached at the other end) into the input hole after which a low buzzing.

    Changing the volume raises the buzz sound a little but not very much.

    The big buzzing starts after I plug the other end of the cable into the output socket on my laptop.

    If I have the volume on the sub-woofer turned down then there is no buzzing, but if turn it up just a little then the buzzing is loud and unaffected by increasing its volume.

    Any help would be appreciated.

    Michael
     
  2. turbo1

    turbo1 TS Maniac Posts: 353

    try using another set of cable,looks like you have a defective plug.
     
  3. redmike

    redmike TS Rookie Topic Starter Posts: 20

    I tried a different one but will get a new one tomorrow.

    I've read about shielded and unshielded etc but I don't know if there is such a thing for a single cable with simple stereo mini phono jacks on each end; or whether or not it would help if they exist.

    Should the length make a difference?

    Thanks for the reply,

    Mike
     
  4. turbo1

    turbo1 TS Maniac Posts: 353

    best way to check is to go to your local electronic shop in your area.

    try to get a good quality of male to male stereo cable that is shielded,im sure there's alot out there to choose from.in my case,if i cant find or too hard to find the set of cable that i need, i build it myself, i just make sure that i get the best quality of cables and plugs.do some soldering,check that nothing is shorted and that's it.

    length can make difference depending on the quality (standard or sub-standard) and thickness of the wire used.i have tried using this type of cable that has the length of 6 feet with no problem.
     
  5. redmike

    redmike TS Rookie Topic Starter Posts: 20

    Well I'm not sure if the cables are shielded or not but the cable has twin flex going into the male mini-plugs, whereas the original one looked line a single cable but had two wires inside.

    Almost silence and no buzzing!

    Thank you very much!

    I spent 30 years working in and around sound studios and I'd say that 90% of the time when there was a technical problem that it was because of cables.

    http://redbourn.notlong.com

    Mike
     
  6. redmike

    redmike TS Rookie Topic Starter Posts: 20

    I wrote too soon -(

    I just plugged the cable into the pc output again and the buzzing is back.

    Just touching the socket causes the buzz.

    No problem earlier though, and I listened to several minutes of audio from the pc.

    Maybe the above will lead to a solution?

    Mike
     
  7. turbo1

    turbo1 TS Maniac Posts: 353

    with the cable plugged into both device,try turning around the plug (while playing music) from subwoofer's input from left to right.

    likewise with the PC's output. i know you know what i mean with this,to check if you have a loose connection either from both jacks (not the plug).

    also try plugging you subwoofer to another AC outlet.
     
  8. redmike

    redmike TS Rookie Topic Starter Posts: 20

    Well after spending ages changing plugs around (sometimes the buzzing stopped but then came back after around 10 minutes) and you know far better than me how frustrating this is, I think we've solved the problem, but it's created another minor problem.

    If I plug my monitor (it has a transformer) into a different wall socket on the other side of the room then all seems well.

    It's been quiet for over two hours now. (fingers and legs are crossed ;-)

    The problem is that I don't want to have a wire going right across the room.

    Would something like this be the answer?

    http://www.provantage.com/tripp-lite-isobar8ultra~7TRPL13X.htm

    Or is there is simpler solution?

    Thanks for you help and patience.

    Michael
     
  9. redmike

    redmike TS Rookie Topic Starter Posts: 20

    Next day and no buzzing :)

    Just need to know what to do in order to have the monitor plugged into the same socket as my PC and sub-woofer etc. without creating the buzzing.

    Thanks,

    Michael
     
  10. turbo1

    turbo1 TS Maniac Posts: 353

    Not sure if that can solve the problem since you’re using a transformer in your monitor. And most likely is interfering with the audio signal from PC to subwoofer.
    If you can find an electrical junction box around the room, then you can ask someone who is experienced to fix this for you. This is having another AC outlet and the permanent solution that I can think of.
     
  11. redmike

    redmike TS Rookie Topic Starter Posts: 20

    The cable that connects to the monitor transformer which came with the monitor when I bought it has a molded 3 pin plug on each end.

    Do you think that removing one of them and reversing the polarity might help?

    There is still no buzzing, but I imagine that the socket that the monitor is plugged into on the other side of the room is on the same 'ring'.

    Thanks,

    Mike
     
  12. jobeard

    jobeard TS Ambassador Posts: 9,350   +622

    your description 'sounds' as if your A/C outlet is ungrounded OR your system is not properly grounded.
     
  13. redmike

    redmike TS Rookie Topic Starter Posts: 20

    I gave you a bit of wrong information.

    The monitor doesn't have a transformer but a "switching power supply" and that seems to be the culprit.

    The suspect a/c socket has an earth cable (3 cables) connected to it but I don't know what the other end is connected to of course.

    I saw a five gang adapter yesterday which is supposed to be both a surge protector (which I don't have) and a noise suppressor and I will get it today and see if it helps.

    Not a bad idea to have my equipment protected from surges anyway.

    Mike
     
  14. jobeard

    jobeard TS Ambassador Posts: 9,350   +622

    OH YEA! big noise generator. Can you separate the monitor from the system;
    say placing the system on the floor and the monitor on the desktop?

    If you have a three pronged plug and a/c outlet, then that cicuit is 'grounded'.
     
  15. redmike

    redmike TS Rookie Topic Starter Posts: 20

    The only thing that has worked until now is to plug the monitor into a socket on the other side of the room.

    That works and the only problem is having the cable go from one side of my room to the other.

    Thanks,

    Mike
     
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